U.S. Vice President Mike Pence has warned Iran "not to test the resolve" of the Donald Trump administration days after the U.S. imposed new sanctions on the Islamic republic over a ballistic-missile test.

Pence made the warning in a February 5 interview amid rising tensions between the two countries.

"Iran would do well to look at the calendar and realize there's a new president in the Oval Office. And Iran would do well not to test the resolve of this new president," Pence told ABC News.

The warning came a day after U.S. Defense Secretary James Mattis called Iran "the single biggest state sponsor of terrorism in the world."

The Trump administration has signaled a more confrontational U.S. policy toward Iran.

Last week U.S. national-security adviser Michael Flynn said, "The days of turning a blind eye to Iran's hostile and belligerent actions toward the United States and the world community are over."

Asked by ABC News how the United States would respond to provocation by Iran, Pence said that the "president said everything's on the table" -- including military action.

Pence also said that Washington is looking into the 2015 nuclear agreement that obligated Iran to significantly restrict its sensitive nuclear activities in exchange for sanctions relief.

"Well, we're evaluating that as we speak," he said.

Pence said that Trump will make a decision in the days ahead.

"He'll listen to all of his advisers, but make no mistake about it. The resolve of this president is such that Iran would do well to think twice about their continued hostile and belligerent actions," Pence added.

Tehran has denied that its missile test violates a UN Security Council resolution or the nuclear deal it struck with world powers, including the United States.

Iranian Foreign Minister Mohammad Javad Zarif wrote last week on Twitter that his country is unfazed by U.S. threats.

"Iran [is] unmoved by threats as we derive security from our people. Will never initiate war, but we can only rely on our own means of defense," Zarif wrote on February 3.